What is the ruling on a man's statement, "Divorce from my wife if she (his sister) returns to him (her husband)," in the event of his sister's return to her husband after their quarrel?

The majority of scholars hold the view that if a man makes his wife's divorce conditional upon an event, the divorce occurs when that event takes place, whether he intended to effect the divorce or merely to threaten, confirm, or prevent something. This is the fatwa we adhere to. Some scholars, such as Sheikh al-Islam Ibn Taymiyyah, are of the opinion that if the husband did not intend to effect the divorce but merely to threaten, confirm, or prevent something, then the divorce does not occur; instead, he is required to pay an expiation for breaking an oath (kaffarat yamin).

Accordingly, the fatwa we adhere to is that this man's divorce took place when his sister returned to her husband. If this divorce does not complete the three divorces, he may take his wife back before her 'iddah (waiting period) expires. However, if his intention was for her to return unwillingly and unhappily, and then her husband appeased her and she returned willingly, then he does not break his oath, as his intention and purpose are considered.